The present invention relates to the plating of metallic strips which may be utilized in a subsequent operation, and more specifically to the plating of aluminum or aluminum alloy strip with nickel, cobalt, nickel-lead or cobalt-lead for a subsequent fluxless brazing operation.
When a coil of strip material of indeterminant length requires treatment thereof to form a final product or as a preliminary stage to a further processing operation, the various stages of treatment may require a large amount of space if the treatment line for the strip retains a horizontal orientation of the strip. As various tanks are required for preliminary steps as well as the actual treatment stage or stages, space will become an important factor in plant design. If space is limited, then the treatment line must be altered to the space available which may result in a less efficient and effective operation. The present invention is utilized to minimize the space requirements of the treatment operation as well as provide certain advantages not found in prior treatment facilities.
The present invention is particularly adapted to a process of plating aluminum strip with nickel, cobalt, nickel-lead or cobalt-lead in preparation for a fluxless aluminum brazing operation as disclosed in U.S. Pat. Nos. 3,482,305 and 3,970,237, wherein aluminum or aluminum alloy parts are brazed together using an aluminum-silicon brazing alloy.
The present invention comprehends the provision of a continuous plating line for a metallic strip of indeterminant length wherein the plating line has a modular design. The modules include (1) the feeding of the metal strip from a coil, (2) preliminary or pretreatment steps for preparation of the strip for plating, (3) continuous electrodeposition of plating material onto the strip, (4) rinsing and drying of the plated strip, and (5) winding of the plated strip onto a second coil.
The present invention also comprehends the provision of a continuous plating line wherein individual spray tanks are utilized for the pretreatment and post treatment stages of plating with an upwardly inclined or sloping orientation of the spray tanks in the pretreatment and post treatment stages. The use of the sloping arrangement of tanks allows the minimization of drag-out of individual solutions or baths and insures a minimum distance between the spray tanks and the plating tanks to avoid reoxidation of the strip surface without the necessity of additional protective devices, such as moisture chambers, fog sprayers, etc.
The present invention further comprehends the provision of a continuous plating line wherein the plating tanks have a novel solution agitation/circulation system. This system provides for recirculation and filtration of the plating solution or bath used in the electrodeposition operation of the plating material and for the directed discharge of the filtered solution behind the anode in the tank through a tubular anode support frame. The direction and distribution of flow of the plating solution permits control of the uniformity and deposition rate of the plating material, thus counteracting the electrical edge effects without the need for specifically shaped anode configurations to suit varying strip width and thickness.
Another object of the present invention is the provision of a continuous plating line which will improve the uniformity of the plating on the moving strip as well as improving the plating efficiency by 40 to 50%.
Further objects of the present invention are to provide a construction of maximum simplicity, efficiency, economy and ease of assembly and operation, and such further objects, advantages and capabilities as will later more fully appear and are inherently possessed thereby.